The imagery of that photo op is more powerful than the apology that wasn't heard by as many people. Actions need to line up with words. I'll give him the benefit of the doubt though. Thanks for the context.
The earliest note of an apology I can find was June 11th. It took Mike Milley 5 days to realize he'd been lied to about the purpose of him following Trump? I could see this being political where he was hoping it would blow over quickly & he wouldn't be dragged in, but only apologizing when it didn't. That's politicking though & I would hope that military generals, in an age of misinformation, are proactive about correcting the record. Another interpretation is that he was 100% on board with the President's plan & miscalculated the impact it would have on him.